Rotary pump

ABSTRACT

The peripheral wall of the pump chamber includes a surface of revolution having its axis coinciding with that of the pump rotor, the latter being provided with radial vanes cooperating with said peripheral wall to divide the chamber into a suction side and a pressure side. A diaphragm having an inner surface forming part of said peripheral wall is urged against the pump rotor by an air cushion enclosed in a space defined by the diaphragm and a bowl seated against the diaphragm&#39;&#39;s outer surface.

United States Patent 1191 Svensson Nov. 13, 1973 ROTARY PUMP [75] StigAke GostaSvensson, Sodertalje,

Sweden [73] Assignee: Alia-Laval AB, Tumba, Sweden [22] Filed: Mar. 10,1972 [21] Appl. No.: 233,692

Inventor:

[30] Foreign Application Priority Data Primary Examiner-C. J. HusarAttorney-Cyrus S. I-Iapgood et a1.

[57] ABSTRACT The peripheral wall of the pump chamber includes a Mar.16, 1971 Sweden 3347/71 surface of revolution having its axis coincidingwith 52 US. c1. 418/156 that of the P rotor the latter being Providedwith 51 1m. (:1. ..F01 5 04 radial vanes cooperating with SaidPeripheral Wall to 158 Field of Search 418/152, 153, 156; divide thechamber into a Suction Side and a Pressure 73/262 side. A diaphragmhaving an inner surface forming part of said peripheral wall is urgedagainst the pump 5 References Cited rotor by an air cushion enclosed ina space defined by UNITED STATES PATENTS the diaphragm and a bowl seatedagainst the diaphragm s outer surface. 2,409,688 10/1946 Momeau 418/1532,738,775 3/1956 Smyser 418/156 4 Claims, 2 Drawing Figures ROTARY PUMPThe present invention relates to pumps of the type comprising a pumprotor which is journalled concentrically in a pump chamber defined by asurface of revolution and which is provided with radially directed vanescooperating with the pump chamber wall to divide the pump chamber into asuction side and a pressure side, the outer edges of the vanes forminggeneratrices of the surface of revolution.

Pumps having a pump rotor journalled eccentrically in the pump chamberand provided with vanes of rubber have been used for pumping liquids,such as milk. Due to the eccentric journalling of the pump rotor, thevanes are folded and unfolded with a high frequency at their attachmentsadjacent to the pump rotor, while dragging against the pump chamber walldue to the centrifugal force. This rapid and severe flexing of the pumprotor vanes causes the vane material to become fatigued so that thevanes are torn off. As soon as the vane has been torn off, the entirepump rotor must be exchanged, which means expensive pump repairs.

An object of the present invention is to provide a durable pump which isalso easy to clean, which latter circumstance is of importance when thepump is used for liquids of the character of food, such as milk.

The pump according to the invention is characterized in that a part ofthe pump chambers peripheral wall is formed by a diaphragm and that abowl engaging the outside of the diaphragm encloses, in cooperation withthe diaphragm, an air cushion which maintains the diaphragm against thepump rotor.

By means of this arrangement, it is no longer necessary to use foldablevanes. According to the invention, the vanes can be quite rigid andconsequently are not worn out through a high frequency folding. Thedividing of the pump chamber into a suction side and a pressure side iseffected by the cooperation of the vanes with the resilient diaphragm,which is urged against the pump rotor and consequently against passingvanes. The diaphragm is subjected only to bulging movements and thus hasa lifetime many times greater than that of the rubber vanes of the priorpumps. In addition, the rubber diaphragm is very cheap to exchange,compared with a pump rotor having rubber vanes.

If the diaphragm has an oval shape and is inserted in a circular space,it lies effectively against the pump rotor, especially under theinfluence of said air cushion.

According to a preferred embodiment of the invention, three pump vanesare used, since this number is sufficient for giving the pump a goodvolumetric efficiency.

The vane leaving the pressure side of the pump chamber, and consequentlylying against the diaphragm, may entrain into the rotation a liquidquantity which is confined between the vane and the diaphragm. To avoidthis effect, the pump rotor vanes are placed obliquely in relation tothe axial direction. This oblique position of the vanes makes itpossible for the aforementioned liquid quantity to flow back in thedirection toward the pump outlet, whereby the volumetric efficiency of,the pump is increased. j

If the outer edges of the pump rotor vanes are parallel to the rotorshaft, the diaphragm is subjected to .a certain wear. This wear can bereduced appreciably by shaping the edges of the vanes substantially asan. arc of a circle, the surface of the pump chamber being shapedcorrespondingly (preferably about spherical).

In this way, bending away of the diaphragm, effected by the vanes, willbe greatest at the center of the diaphragm.

The invention is explained more in detail below, reference being made tothe accompanying drawing in which FIG. 1 is a sectional view of anexample of the new pump, taken at right angles to the axis of rotationof its rotor, and

FIG. 2 is a longitudinal sectional view of the same example, showing therotor in side elevation.

In FIG. 1, a pump housing 1 has a generally spherical pump chamber 2provided with an inlet 3 and an outlet 4. A pump rotor 5 with threevanes 6 is journalled concen'trically in the pump chamber 2. Thedirection of rotation of the pump rotor is indicated by an arrow, shownin the pump chamber. In the position of the rotor 5 as shown in FIG. 1,an oval rubber diaphragm 7 lies in a circular space 8 against the pumprotor body 5 proper and the two upper vanes 6. The rubber diaphragm isclamped in the pump housing 1 by means of an inverted bowl 9, which issecured to the housing 1 by suitable clamping means (not shown) ofconventional form. The bowl 9 encloses above the diaphragm an aircushion, which keeps the diaphragm pressed against the rotor 5.

As shown in FIG. 2, the edge of each vane 6 forms an arc of a circle sothat it conforms to the arcuate shape of the chamber wall 2a. Also, asshown in FIG. 2, the vanes As shown in FIG. 2, the edge of each vane 6forms an arc of a circle so that it conforms to the arcuate shape of thechamber wall 2a. Also, as shown in FIG. 2, the vans are disposedobliquely in relation to the axial direction. The pump rotor 5 has twogudgeons l0 journalled in corresponding recesses in the pump housing,and the right-hand gudgeon is connected to a shaft 11 of a driving motor(not shown). The lead-through of the shaft 11 in the pump housing issealed by means of a gasket 12. The right-hand gudgeon 10 has adiametrical groove (not shown) which receives a corresponding drivingprojection (not shown) on'the shaft 11. When the rotor 5 is turned sothat said groove extends vertically, the rotor can easily be lifted fromthe pump housing so as to'be inspected and cleaned.

When the pump rotor rotates in the direction of the arrow, there isformed in the left-hand part of the pump chamber 2 (FIG. 1) a suctionside which, by means of the lower vane 6, is separated from a pressureside formed in the right-hand part of the pump chamber. The right-handupper vane 6 will come into contact with the diaphragm 7 and slide pastit while lifting it against the action of the air pressure in the bowl8. Thus, the sealing (necessary for the pumping function) between thisvane and the diaphragm is obtained. Due to the arcuate shape and theoblique position of the vane, the diaphragm is lifted successively andmostly at its center, whereby it is subjected to minimum wear. lf

' the edges of the vanes 6 were parallel to the axis of rotation, thevanes would, when passing the diaphragm, entrain a liquid quantityconfined between the diaphragm and the vanes. Through said obliquepositioning of the vanes, however, such liquid quantity will slide alongthe entraining vane in the direction toward the pump outlet 4, wherebythe volumetric efficiency of the pump is increased.

l. A pump comprising means defining a pump chamber, said chamber havinga peripheral wall including a surface of revolution and also having aninlet and an outlet, a rotor journalled in the housing for rotation insaid chamber about an axis concentric to said surface of revolution, therotor having vanes extending radially outward and cooperating with saidperipheral wall to divide the chamber into a suction side and a pressureside communicating with said inlet and said outlet, respectively, theouter edges of said vanes forming generatrices of said surface ofrevolution, said means including a flexible diaphragm having an innersurface forming part of said peripheral wall and engageable with eachsaid vane along the entire outer edge thereof, a

ing a shapecorresponding to said arc.

4. A pump according to claim 3, in which said vanes extend obliquelyrelative to said rotation axis.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 1 IDated November 13 1973 l lg Ake Gosta Svensson It is certified thaterror appears in the above-identified patent Y and ,that said LettersPatent are hereby corrected as shown below:

7 Col. 2', lines 27, 2s, 29, and 30 should be deleted.

Col 2, line 34, "vans" should be --vanes Claim 2,,line2, "s'i'ad" shouldbe --said--.

7 Signed anc l 'sealed this 6th day of Augustl974.

(SEAL) Attest: MCCOY M.- GIBSON; JR; C. MARSHALL DANN Attesting OfficerCommissioner of Patents

1. A pump comprising means defining a pump chamber, said chamber havinga peripheral wall including a surface of revolution and also having aninlet and an outlet, a rotor journalled in the housing for rotation insaid chamber about an axis conceNtric to said surface of revolution, therotor having vanes extending radially outward and cooperating with saidperipheral wall to divide the chamber into a suction side and a pressureside communicating with said inlet and said outlet, respectively, theouter edges of said vanes forming generatrices of said surface ofrevolution, said means including a flexible diaphragm having an innersurface forming part of said peripheral wall and engageable with eachsaid vane along the entire outer edge thereof, a bowl seated against theouter surface of said diaphragm and cooperating therewith to form anenclosed space, and an air cushion in said space urging the diaphragmagainst said rotor.
 2. A pump according to claim 1, in which said spaceis circular, siad diaphragm having an oval shape.
 3. A pump according toclaim 1, in which each of said vane edges extends lengthwise of saidaxis in substantially an arc of a circle, said surface of revolutionhaving a shape corresponding to said arc.
 4. A pump according to claim3, in which said vanes extend obliquely relative to said rotation axis.